Field of the Invention
The present invention relates to a position detection sensor which detects a position of a linear member, and a manipulator including the position detection sensor.
Description of Related Art
In recent years, studies of medical treatment using robots have been performed to save labor in health-care facilities. In particular, in the field of surgery, there are various suggestions for a manipulator system in which treatment is performed to a patient using a manipulator having multiple degrees of freedom (multiple joints).
For example, a robot surgical system described in U.S. Pat. No. 7,930,065 includes one or more manipulators provided near a surgical table, and a controller which enables an operator to manipulate the manipulator while observing a surgical field. The robot surgical system includes an observation device, and a plurality of treatment tools which are removable from the manipulator.
A main body of the treatment tool is configured in such a manner that a plurality of segments are connected to each other via connection portions. One or more degrees of freedom are given to the manipulator by bending each connection portion. A channel is formed in the main body. An optical fiber is inserted into the channel. A sensor controller is attached to a proximal end portion of the optical fiber.
The optical fiber and the sensor controller are used to detect a bending amount of the main body of the treatment tool. Hereinafter, this is described in detail.
Four cores are arranged in the optical fiber so as to be at the same distance from a central axis of the optical fiber. In a cross section of the optical fiber, these cores are arranged so that the direction in which one of two sets of paired cores faces is orthogonal to the direction in which the other set faces.
In each core, a Fiber Bragg Grating which is a type of diffraction grating is provided at the same position in a longitudinal direction. The sensor controller is connected to two cores in the set. When the optical fiber is bent, one of the two cores in the set becomes longer than the other. The sensor controller can detect this state using the following method.
A mirror which reflects a part of light is attached to a distal end of each core. The sensor controller outputs light having a different wavelength from a proximal end of each core to the distal end thereof. The sensor controller detects an amount of the light reflected and returned by the mirror. Since the amount of the light reflected and returned by the mirror is changed in accordance with a bending amount of the core, the bending amount of the treatment tool into which the optical fiber is inserted can be detected by detecting the amount of the light.